The present invention is related to a cartridge actuated device and more particularly to the safing of a gas driven cartridge having no moving parts.
Increased aircraft performance envelopes and variable mission profiles have resulted in more complex aircrew automated escape systems (AAES). Because more stringent AAES performance requirements are needed to ensure safe crew-member recovery, additional maintenance and safety problems with potential consequent degradation of AAES performance and reliability have become apparent. In order to obtain AAES performance improvement, more accurate event sequencing and timing has been required. However, current AAES technology can provide pyrotechnic delay cartridges with an accuracy of only .+-.15% over the temperature range of -65.degree. F. to 200.degree. F. These pyrotechnic time delay cartridges provide nominal fixed time delays for the entire aircraft operational envelope, which are not optimum for all ejection conditions.
Because of the above mentioned current AAES problem areas and others, and the potential solution offered by fluidics, efforts to investigate the feasability of incorporating fluidic technology in AAES has resulted in the development of a Flueric Cartridge Initiator (FCI), disclosed in U.S. Pat. No. 4,033,267, issued July 5, 1977, to applicants herein. The FCI patent, incorporated herein by reference, discloses a fluidic device which operates on a gas flow phenomena where resonance takes place in a stepped cylindrical tube when a jet of gas is directed at it. This gas resonance generates extremely hot temperatures, e.g., on the order of 2000.degree., within a few milliseconds and can be used to ignite explosives, pyrotechnics or propellants in times as short as 3 milliseconds.
The FCI interfaces with a fluidic sequence (FS) which controls its actuation. The sequencer mode of operation provides one output from a cool/warm gas generator. A second input (the firing signal) occurs later, at a time specified by the sequencer depending on the ejection parameters. By itself, this requirement for the above referenced FCI to be compatible with the sequencer does not require the FCI to have AND logic built in. The same thing could be done with a simpler NOR logic configuration. For NOR logic, the first signal can be used to inhibit operation while the second signal comes on. The firing signal would then be the absence of the inhibiting signal. NOR logic, however, is inadequate to insure against inadvertent ignition if the FCI is accidentally connected to a gas supply. One input could not cause ignition but the other possibly could. Thus, to insure safety in the event that gas is inadvertently connected to either of the two inputs of the FCI, it must have an AND logic capability. However, the FCI of U.S. Pat. No. 4,033,267 does not disclose AND logic capability means for safing the device so that accidental ignition of the primary explosives, etc., is made extremely unlikely.